Restless quest

The journalists at the panel discussion were hanging on Ellen Stofan's every word. NasaThe National Aeronautics and Space Administration, responsible for the US space programme.'s chief scientist had just made an astonishing prediction: "I think we're going to have strong indications of life beyond Earth within a decade, and I think we're going to have definitive evidence within 20 to 30 years."

That was in 2015 - so if Stofan was right, the discovery of alien life is imminentAbout to happen..

Yesterday saw the launch of the Peregrine 1 Moon lander. Although it soon ran into problems, it is only the first of a dozen missions scheduled for 2024 which could shed light one of humanity's biggest questions: are we alone in the universe?

Peregrine 1 should investigate a strange area of the Moon called the Gruithuisen Domes. They seem to be the result of volcanic activity which, on Earth, could only take place with the aid of water.

This key constituent of life is central to the search for aliens. And according to Paul Hertz, Nasa's former head of astrophysicsThe study of the physical laws and ideas that explain how the stars and planets work. , the Milky WayThe galaxy that contains our solar system. It has the structure of a disc, but looks to us like a band because we are inside it. is "a soggy place".

Scientists believe that there are oceans below the surface of two of Jupiter's moons, Europa and Ganymede, and also one of Saturn's, Enceladus. Nasa plans to launch a spacecraft to investigate Europa in October.

There could also once have been oceans on Mars, though not all scientists agree on this. Nasa's Curiosity rover has already discovered fixed nitrogen and organic molecules containing carbon on the planet - both essential for life forms like our own.

But finding favourable conditions for human life is not the same as finding alien life. With this in mind, Nasa has just started work on a space telescope called the Habitable Worlds Observatory (HWO). A team of 60 scientists has been assembled to design it.

So far astronomers have discovered over 5,500 worlds orbiting other stars. The HWO's mission will be to look for life on 25 worlds similar to our own.

They will be within 100 light yearsA unit of measurement equal to the distance that light travels in one year, which is 9.4607 times 1012 km. That's nearly 6 million million miles! of Earth and roughly the same size. They will also have temperatures which are neither too hot nor too cold for water to exist. The HWO will study their atmospheres for signs of life such as oxygen and methaneA particularly strong greenhouse gas produced by fossil fuels and cattle., using ultravioletA form of electromagnetic radiation that cannot be seen by the human eye. and infraredA type of electromagnetic radiation (a wave with electricity). The wave is longer than light which humans can see and shorter than microwaves. light.

According to leading astronomer Marc Postman: "This is the first telescope ever built that will be able to really address, in a scientific way, how common life is beyond the solar system."

Can we believe it this time?

Yes: There are all kinds of exciting developments in space exploration, including private enterprises like the Peregrine 1 mission. The HWO shows that Nasa is really committed to the search for aliens.

No: After decades of searching, we have still found no evidence of alien life. The HWO will probably not be ready for launch until 2040. The Europa probe is not scheduled to reach Jupiter until 2030.  

Or... Even if these missions establish that there is no other life on habitable worlds, they should not be considered a waste of time. They would prove that humans have a unique place in the universe.